Method of encasing a toroidally shaped object with a heat shrinkable covering

ABSTRACT

Heat shrinkable tubing is placed around an article such as a toroid, having a hole extending therethrough, so that the axis of the tubing is coaxial with the axis of the toroid. The tubing is heated until the ends of the tubing shrink to the dimension of the inside diameter of the toroid. The ends of the tubing, while still warm and soft, are then folded within the toroid, overlapped, and secured together to encase the toroid within the tubing.

United States Patent 1191 Bielawski [54] METHOD OF ENCASING A TOROIDALLY SHAPED OBJECT WITH A HEAT SHRINKABLE COVERING [75] Inventor: Jooeph J. Bielawskl, Skokie, Ill.

Assignee:

porated, New York, N.Y.

Filed: Sept. 2, 1971 Appl. No.: 177,363

us. Cl. ..53/13, 53/30, 53 33, 156/86, 336/209 Int. Cl. ..B65b 53/06 Field or Search ..53/13, 30, 32, 33, 204-, 156/8586, 294; 206/46 '1, 46 Y, 46 FM; 229 010. 12; 339/209 5 6] Relerences Cited UNITED STATES PATENTS 2,275,967 3/1942 Keillor et al ..336/209 I. D. OF TOROID Western Electric Company, lncor- {[1 11 ,Heat shrinkable tubing is placed around an article such as a therethrough, so that the axis of the tubing is coaxial [4 1 Jan. 16, 1973 3/l959 l0/l96l 2/l966 12/1970 9/l97l Prir nary Examiner-Robert L. Spruill I j; Attorney-W. M. Kain et al.

ABSTRACT toroid, having a hole extending with the axis of the toroid. The tubing is heated until the ends of the tubing shrink to the dimension of the inside diameter of the toroid. The ends of the tubing, while still warm and soft, are then folded within the toroid, overlapped, and secured together to cncase the toroid within the tubing.

13 Claims, 6 Drawing Figures PATENTEDMN IS m5 3.710.531

INVENTOR J. J. BIELAWSKI BY M4, 3:451

6? ATTO NEY I METHOD OF ENCASING A TOROIDALLY SHAPED OBJECT WITH A HEAT SHRINKABLE COVERING BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention relates to a method of encasing toroidally shaped objects, and in particular to a method of encasing a toroid within a heat shrinkable tubing.

2. Description of the Prior Art In manufacturing electrical devices such as transformers or inductors having toroidally shaped cores, it is necessary to provide an insulating coating, or encasing, over the entire surface of the core before wires are wound thereon to form the required windingsOne present method of insulating toroidally shaped transformer or inductor cores includes winding a tape around the core. Tape winding cores, however, is time consuming if performed by hand and requires a significant amount of apparatus if performed mechanically. Other methods of insulating cores contemplate spraying multiple coats of enamel onto the cores, with a drying period after each coating, to form an insulating finish thereon, or spraying an epoxy powder onto a heated core, the epoxy powder melting and fusing when it engages the heated core and solidifying upon cooling to form an insulating finish thereon. Enamel and epoxy coating cores, however, in addition to spraying, oven heating, and drying equipment, requires waste treatment facilities, such as water purification facilities to cleanse water used as a backwash in spray booths, and requires that the trays supporting the cores during spraying be periodically stripped of the enamel or epoxy. This is undesirable as adding both time and expense to the insulating operation. Further, none of SUMMARY OF THE INVENTION In accordance with the present invention, the surface of an article having a hole extending therethrough is covered by placing a shroud of shrinkable material about the article with sections thereof extending in opposite directions from the periphery of the article by amounts which are greater than the distance between the hole and the periphery of the article. The extending sections of the shroud are shrunk to draw the sections against the surface of the article until the cross-sectional dimensions of the extending sections of the shroud are equal to the dimensions of the hole. The extending sections of the shroud are then tucked, overlapped, and secured together within the hole to provide a covering on the surface of the article.

Preferably, the article is a toroid and the shroud is a length of heat shrinkable tubing placed around the tomid such that the axes of the tubing and of the toroid are coaxial, the tubing being shrinkable to at least the dimension of the inner diameter of the toroid and being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid. The tubing is heated to shrink the tubing around the toroid until the diameter of each projecting end shrinks to the size of the inner diameter of the toroid. The projecting ends of the shrunk tubing are then tucked, overlapped and secured together within the toroid to encase the toroid within the tubing.

The overlapped ends of the tubing within the toroid are secured together by any one of several methods.

Generally, the ends are secured together by a heated roller, the roller being of such a size as to fit within the toroid after the ends of the tubing are overlapped therein. The heated roller pressingly. engages the length of the overlapping ends to additionally heat the ends to draw them tightly together within the toroid to encase the toroid within the tubing. Alternatively, the roller is heated to a temperature sufficient to melt the tubing when it is brought into engagement therewith, and is passed over the length of the overlapping ends of the tubing to melt and to fuse together the ends of the tubing within the toroid.

Another method of securing together the overlapping ends of the tubing is to apply powered metal to at least one of the projecting ends before the ends are tucked within the toroid, the ends then being tucked within the toroid such that the powered metal is between the overlapping portions. Inductively heating the powered metal with an induction coil causes the overlapping ends to melt and to fuse together to seal the toroid within the tubing. A further method of securing together the overlapping ends of the tubing contemplates applying an adhesive to at least one of the projecting ends before the ends are tucked within the toroid, the ends then being tucked within the toroid such that the adhesive is between the overlapping portions.

Other objects, advantages and features of the invention will be apparent-upon considerationof the following detailed description when taken in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a length of heat shrinkable tubing extended around a toroidally shaped object to be packaged;

FIG. 2 is a perspective view showing the heat shrinkable tubing of FIG. 1 shrunk around the toroid;

FIG. 3 is a perspective view showing the shrunk tubing partially tucked within the toroid;

FIG. 4 is a plan view showing a heated roller securing the ends of the tubing within the toroid;

FIG. 5 is a perspective view showing the heat shrinkable tubing shrunk around the toroid, similar to that shown in FIG. 2, but having powdered metal applied to one of the projecting ends of the tubing; and

FIG. 6 is a perspective view showing inductive heating apparatus for heating the powdered metal to seal the tubing within the toroid after the ends of the tubing shown in FIG. 5 have been tucked and overlapped within the toroid.

DETAILED DESCRIPTION Referring to FIG. 1 of the drawings, there is shown a toroidally shaped transformer or inductor core 11 around which is placed a shroud, or length, of heat shrinkable plastic tubing 12, the longitudinal axis of the core 11 being parallel, or coaxial, with the-longitudinal axis of the tubing 12. The tubing 12 is a standard heating thereof, to at least the inner diameter of the core, and is of a sufficient length to allow tucking and overlapping of the projecting ends thereof, when shrunk, within the core. The core 11 and the tubing 12 are maintained in their respective orientations by any suitable holding devices (not shown), the core 11 preferably being supported within its center by a holding device and the tubing 12 being supported by the core 1 1. However, the tubing 12 may be supported by a holding device with the core 11 supported and positioned within the tubing.

To shrink the tubing 12 around the core 11, a jet of hot air from a conventional hot air gun 13 may be directed at the tubing 12, as shown in FIG. 2, until the diameter of each of the projecting ends of the tubing 12 shrinks to the inside diameter of the toroidally shaped core 11. The tubing 12 could likewise be shrunk around the core 11 by placing the tubing 12 and the 7 core 11 in any conventional heating chamber. The projecting ends of the tubing 12, while still warm and soft from the jet of hot air, are then tucked within the inner portion of the core 1 l as shown in FIG. 3, such that the ends of the tubing overlap within the core. The ends of the tubing are tucked within the core 11 by hand or by any suitable mechanical device.

To secure the overlapping ends of the tubing 12 to encase, or package, the core 11 within the tubing the core is supported, as shown in FIG. 4, between a driving roller 13 and a heating roller 16, the driving roller 14 engaging the plastic tubing on the outer periphery of the core 1 1 and the heating roller 16 engaging the overlapping ends of the plastic tubing 12 on the inner periphery of the core 1 1. Operation of the driving roller 14 rotates the core 1 1 so that the heating roller 16 rolls over and pressingly engages the length of the overlapping ends of the tubing 12. Generally, the heating roller 16 is not sufficiently hot to melt the tubing 12, and operates to additionally shrink and press together the overlapping ends of the tubing so that they are drawn tightly together. However, the heating roller 16 may be sufficiently hot to sinter or to melt and fuse together the overlapping ends of the plastic tubing to provide a coherent plastic package around the core 1 l. The core 1 1 is then removed from between the driving roller 14 and the heating roller 16 and the plastic tubing thereon is cooled.

A second method of packaging the core 11 within the plastic tubing 12 contemplates fusing the overlapping ends of the tubing 12 by inductively heating a metal'powder spaced between the overlapping ends, the metal powder being comprised of a metal, such as iron, which may be inductively heated. A powdered metal 17 is applied around the periphery of at least one of the projecting ends of the tubing 12, as shownin FIG. 5, either prior to shrinking the tubing 12, or after the tubing 12 has been shrunk around the core 11 until the diameter of the projecting ends of the tubing 12 shrinks to the inside diameter of the core 11 as shown in FIG. 2, but prior to tucking and overlapping the projecting ends of the tubing within the core as shown in FIG. 3. The powdered metal 17 is applied around the periphery of the projecting end by any suitable means, such as by coating the projecting end with an adhesive and then inserting the adhesive coated end into a supply of powdered metal. The ends of the tubing 12 are then tucked and overlapped within the inner portion of the core 11, as shown in FIG. 3, such that the coatingof powdered metal is between the overlapped ends. To fuse the overlapped ends of the tubing 12 together to package the core 11 therein, the core is placed within the turns of an induction coil 18, as shown in FIG. 6, and current is provided from a power source 19 through the coil 18 to inductively heat the powdered metal spaced between the overlapping ends of the tubing 12 to melt and to fuse the overlapping ends together.

In accordance with another method of packaging the core, an adhesive is carried on one or both of the projecting ends of the tubing and bonds the ends of the tubing together when they are overlapped within the core after the tubing has been shrunk around the core. Preferably, curing of the adhesive is accelerated by heating the adhesive, such as by pressingly engaging the overlapped ends with the heating roller 16, as shown in FIG. 4.

While several embodiments of the invention have been described in detail, it is understood that various other modifications and embodiments may be devised by one skilled in the art without departing from the spirit and scope of the invention. For example, while the invention has been described with respect to the encasing of a toroidally shaped transformer or inductor core, any toroidally shaped object may similarly be encased. Also, the method of the invention is not limited to the encasing of toroids, but may be extended to the encasing of any object having a centered passageway extending therethrough. A cube having a centered passageway extending therethrough may, for example, be packaged in accordance with the method of the invention by placing a suitable heat shrinkable tubing around the cube and by heating the tubing until the ends of the tubing shrink to the diameter of the passageway. The ends of the tubing are then folded and overlapped within the passageway and secured together in accordance with any one of the described methods. Further, it is not necessary that a roller be used to heat and to pressingly engage the overlapping edges of the tubing. Any other suitable device may be used, such as a conically shaped tool.

Additionally, practicing the invention is not necessarily limited to the use of heat shrinkable plastic tubing. Rather, a shroud of shrinkable material other than tubing may be placed around an article having a hole, or passageway, extending therethrough, with sections thereof extending in opposite directions from the periphery of the article. The material may then be shrunk and the extending sections folded, overlapped and secured together within the hole.

What is claimed is:

l. A method of covering the surface of an article having a hole extending therethrough, which comprises:

placing a shroud of shrinkable material about the article with sections thereof extending in opposite directions from the periphery of the article by amounts which are greater than the distances between the hole and the periphery of the article;

shrinking the extending sections of the shroud to draw the sections against the surface of the article until the cross-sectional dimensions of the extending sections of the shroud are equal to the dimension of the hole;

tucking and overlapping the extending sections of the shroud within the hole; and

securing together the overlapping sections.

2. The method as recited in claim I, wherein securing together the overlapping sections comprises heating the overlapping ends to secure them together.

3. The method as recited in claim 2, wherein an inductively heatable powdered metal is provided between the overlapping sections and heating the sections comprises inductively heating the powdered metal to heat the sections and to fuse them together.

4. The method as recited in claim 2, wherein securing together the overlapping sections comprises applying an adhesive between the sections to bond the sections together.

5. A method of encasing a toroidally shaped object, which comprises:

placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid;

heating the tubing to shrink the tubing around the toroid, the tubing being heated until the diameter of the projecting ends shrinks to the size of the inner diameter of the toroid;

tucking and overlapping the projecting ends of the shrunk tubing within the toroid; and

securing together the overlapped ends to encase the toroid within the tubing.

6. The method as recited in claim 5, wherein heating the tubing to shrink the tubing comprises blowing heated air onto the tubing.

7. The method as recited in claim 5, wherein securing together the overlapping ends comprises heating the overlapping ends to fuse them together.

8. The method as recited in claim 7, wherein heating the overlapping ends to fuse them together comprises pressingly engaging the overlapped ends within the toroid with a heated tool to melt and to fuse the ends together.

9. A method of packaging a toroidally shaped object, which comprises:

placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid;

heating the tubing to shrink the tubing around the toroid, the tubing being heated until the diameter of the projecting ends shrinks to the size of the inner diarneter of the toroid' applying an inductively heatable powdered metal to at least one of the projecting ends;

tucking and overlapping the projecting ends of the shrunk tubingwithin the toroid so that the powdered metal is spaced between the overlapping ends; and

inductively heating the powdered metal on the overlapping ends to heat the ends and fuse them together to package the toroid within the tubing.

10. A method of encasing a toroidally shaped object,

which comprises:

placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid;

heating the tubing to shrink the tubing around the toroid, the tubing being heated until the diameter of the projecting ends shrinks to the size of the inner diameter of the toroid;

tucking and overlapping the projecting ends of the shrunk tubing within the toroid; and

continuing to heat the tubing to shrink the tubing an additional amount to further draw the overlapping ends of the tubing more tightly together and into tighter contact with the toroid to form a seal and to encase the toroid within the tubing.

11. A method of covering the surface of a toroidally shaped object, which comprises:

placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid;

heating the tubing to shrink the tubing around the to roid, the tubing being heated until the diameter of the projecting ends shrinks to the size of the inner diameter of the toroid;

applying an adhesive to at least one of the projecting ends; and

tucking and overlapping the projecting ends of the 

1. A method of covering the surface of an article having a hole extending therethrough, which comprises: placing a shroud of shrinkable material about the article with sections thereof extending in opposite directions from the periphery of the article by amounts which are greater than the distances between the hole and the periphery of the article; shrinking the extending sections of the shroud to draw the sections against the surface of the article until the crosssectional dimensions of the extending sections of the shroud are equal to the dimension of the hole; tucking and overlapping the extending sections of the shroud within the hole; and securing together the overlapping sections.
 2. The method as recited in claim 1, wherein securing together the overlapping sections comprises heating the overlapping ends to secure them together.
 3. The method as recited in claim 2, wherein an inductively heatable powdered metal is provided between the overlapping sections and heating the sections comprises inductively heating the powdered metal to heat the sections and to fuse them together.
 4. The method as recited in claim 2, wherein securing together the overlapping sections comprises applying an adhesive between the sections to bond the sections together.
 5. A method of encasing a toroidally shaped object, which comprises: placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid; heating the tubing to shrink the tubing around the toroid, the tubing being heated until the diameter of the prOjecting ends shrinks to the size of the inner diameter of the toroid; tucking and overlapping the projecting ends of the shrunk tubing within the toroid; and securing together the overlapped ends to encase the toroid within the tubing.
 6. The method as recited in claim 5, wherein heating the tubing to shrink the tubing comprises blowing heated air onto the tubing.
 7. The method as recited in claim 5, wherein securing together the overlapping ends comprises heating the overlapping ends to fuse them together.
 8. The method as recited in claim 7, wherein heating the overlapping ends to fuse them together comprises pressingly engaging the overlapped ends within the toroid with a heated tool to melt and to fuse the ends together.
 9. A method of packaging a toroidally shaped object, which comprises: placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid; heating the tubing to shrink the tubing around the toroid, the tubing being heated until the diameter of the projecting ends shrinks to the size of the inner diameter of the toroid; applying an inductively heatable powdered metal to at least one of the projecting ends; tucking and overlapping the projecting ends of the shrunk tubing within the toroid so that the powdered metal is spaced between the overlapping ends; and inductively heating the powdered metal on the overlapping ends to heat the ends and fuse them together to package the toroid within the tubing.
 10. A method of encasing a toroidally shaped object, which comprises: placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid; heating the tubing to shrink the tubing around the toroid, the tubing being heated until the diameter of the projecting ends shrinks to the size of the inner diameter of the toroid; tucking and overlapping the projecting ends of the shrunk tubing within the toroid; and continuing to heat the tubing to shrink the tubing an additional amount to further draw the overlapping ends of the tubing more tightly together and into tighter contact with the toroid to form a seal and to encase the toroid within the tubing.
 11. A method of covering the surface of a toroidally shaped object, which comprises: placing a length of heat shrinkable tubing around the toroid, such that the axes of the tubing and of the toroid are parallel, the tubing being constructed of a material that is shrinkable to at least the inner diameter of the toroid and the tubing being of a sufficient length to allow tucking and overlapping of the projecting ends of the tubing, when shrunk, within the toroid; heating the tubing to shrink the tubing around the toroid, the tubing being heated until the diameter of the projecting ends shrinks to the size of the inner diameter of the toroid; applying an adhesive to at least one of the projecting ends; and tucking and overlapping the projecting ends of the shrunk tubing within the toroid so that the adhesive is spaced between the overlapping ends to bond the ends together.
 12. The method as recited in claim 11, wherein the adhesive has an accelerated curing time in response to heating thereof, further comprising additionally heating the overlapping ends to accelerate the curing of the adhesive.
 13. The method as recited in claim 12, wherein additionally heating the overlapping ends comprises pressingly engaging tHe overlapping ends with a heated tool. 